Tag Nodes With Chef Roles Using cloudformation

Question

So my goal is to launch say 100 nodes in the cloud using cloudformation and I would like to tag nodes with chef roles within my cloudformation script instead of using knife. I have setup my cloudformation nodes to automtically register themselves with the chef server and I want to use report their role to the chef server so that chef server installs the proper cookbooks on each node (depending on the node roles). I know this is possible with knife but I want to bury the node role within my cloudformation script.

How can I do so?

Answer 1

I use Puppet, which is of course slightly different to Chef, but the same theory should apply. I send a JSON object as the user data when launching a new instance (also via CloudFormation), then access this data in Puppet to do dynamic configuration.

Puppet handles a lot of this automatically - e.g. it will automatically set the FACTOR_EC2_USER_DATA environment variable for me, so I just need to parse the JSON in to variables such as $role and $environment, at which point I can dynamically decide which role the instance should be assigned.

So as long as you can find some way to access the user data within Chef, the same approach should work.

Answer 2

I do this with chef. I usually put a json file in S3 which describes the roles the machine needs to use. I create an IAM user in CloudFormation which can access the S3 bucket. Then, in my user data script, I first grab the file from S3 and then run chef-client -j /path/to/json/file. I do the same thing with the validation key, fwiw, so that the node can register itself.

HTH